Guard board for paper-making machines



Dec. 28 1926.

H. M. ASHBY GUARD BOARD FOR PAPER MAKING MACHINES Filed August 2, 1922 Patented Dec. 28, 1926.

UNITED STATES PATENT OFFICE.

HOLDON M. ASHBY, 0F ALBANY, NEW YORK, ASSIGNOB TO F. C. HUYCK & SONS, OF RENSSELAER, NEW YORK, A CORPORATION OF NEW YORK.

GUARD BOARD FOR PAPER-MAKING MACHINES.

Application filed August 2, 1922. Serial No. 579,124.

The invention relates to a guard-board construction for paper making machines.

Guard-boards of the type to which the invention relates are commonly used for cleaning and drying the felt jacketed couch rolls of Fourdrinier paper making machines. The guard-boards heretofore in general use for this purpose have been provided with a felt-engaging blade or board which consists of a hard maple plank aboutone inch thick and six or seven inches wide, the edge of which is beveled or sharpened to afford a comparatively narrow bearing surface for engaging the felt jacket of the couch roll. Owing to the gradual increase in the width of the bearing surface as the board wears, it is removed and the bevel replaned at more or less frequent intervals depending upon the rapidity of the wear, with a resulting loss in production due to the stopping of the machine while the board is being removed and replaced. As the board wears and the width of the bearing edge increases, it is also necessary to increase the pressure with which it is forced against the felt jacket in order to remove the requisite amount of water from the jacket. This increased pressure not only increases the wear on the expensive jacket but also adds to the power required to run the machine. To avoid making subsequent adjustments, the operator usually forces the resharpened board against the felt jacket with an unduly heavy pressure, thus increasing the wear on the board and jacket. This heavy pressure with a comparatively thin bearing edge is also likely to sharply indent the jacket and subject it to a circumferential strain tending to cause it to creep and become distorted so that its action is rendered defective and its life shortened.

The above defects which are inherent in the prior guard-board constructions are eliminated by the present invention, the primary feature of which consists in the provision of a jacket engaging blade having a uniform thickness substantially the same as the width of the bearing edge which will efficiently cooperate with the felt jacket of the couch roll, so that as the blade wears away, this width of bearing edge will be maintained, thus ensuring eflicient cooperation between the blade and jacket with a minimum Wear on each. For the most efficient cooperation with the felt jacket, the

bearing edge should be of a width sufficient to avoid sharply indenting the jacket when pressed against it with the force requisite to properly clean and dry it and still not sutficient to require an excessive pressure in order to secure this result. The bearing edge should also act uniformly on the jacketed surface of the couch roll from end to end. The blade must therefore be comparatively thin and it must be accurately guided and pressed uniformly against the jacketed surface of the couch roll throughout its length. Since hard maple has proved particularly well adapted to cooperate with the felt jack ets of couch rolls, the jacket engaging blade is preferably made from this material, and since experience has demonstrated that the most efficient action of a board of this materlal is secured with a bearing surface approximately in width, the blade is made approximately of this thickness. In order that the edge of this thin blade may be pressed evenly and uniformly against the jacket, means is provided for applying a uniform pressure to the blade at intervals throughout its length. This means may be of any suitable character but preferably comprises a shaft provided with one or more weighted arms and carrying a series of gears which engage racks arranged at intervals along the blade to transmit thereto, at corresponding intervals, the pressure due to the weights.

The preferred form of the invention is shown in the accompanying drawings in which Figure 1 is a front elevation showing one end of the guard-board, and Fig. 2 is a sectional View on line 22 of Fig. 1.

In the drawings the guard-board embodying the preferred form of the invention is shown in position in a paper making machine to act on the felt jacket 2 of the couch roll 4. The guard-board comprises a rigid back-board adapted to be secured in fixed position above the couch roll, a thin jacket engaging blade mounted for free vertical movement on the back-board, and means for pressing the edge of the blade uniformly against the jacket. As shown, the backboard is in the form of a metallic channel bar 6 which extends across the machine and has its ends rigidly secured in the guardboard brackets 8 by clamping screws 10.

The jacket engaging blade is in the form of a thin comparatively narrow blade 12 of uniform thickness and it is retained and guided between the face of the backboard and a series of retaining and guiding plates 1 1 secured at intervals to the front of the back-board. The thickness of the blade is such that as the blade wears away, its lower edge continually presents a jacket engaging surface having a width which will efiiciently clean and dry the jacket without sharply indenting it or applying an excessive pressure thereto. The wear on the jacket is thus reduced to a minimum and its proper operation upon the paper stock throughout its life is ensured. The loss of production due to the stopping of the machine for the rebeveling or sharpening of worn guardboards is also eliminated as is also the loss in etliciency due to the use of boards, the jacket engaging edges of which are either too wide or too narrow for eliicient use. For the reasons already stated, the blade is preferably a hard maple strip substantially onefourth of an inch thick and of convenient width, say approximately six or seven inches.

The means for pressing the blade against the couch roll jacket comprises a shaft 16 mounted on the back-board parallel to the blade 12 and having secured thereto at intervals a series of gears 18 engaging racks 20 which are connected to apply pressure to the blade. In order to permit the convenient removal and replacement of the blade, the racks are preferably secured to a pressure transmitting plate mounted to slide between the retainer plates and the face of the backboard and to engage ant transmit pressure to the upper edge of the blade 12. The racks project through slots formed in the back-board back of the retaining plates. The ends of the shaft are journaled in bearing plates 2i which may be secured to the ends of the back-board by the truss rods 26. An arm 28 is connected with each end of the shaft and carries an adjustable weight 30 which determines the force with which the blade is pressed against the acket. In order that the weighted arms may be readily adj usted to extend horizontally from the shaft, each arm is secured to a sleeve 32 loosely mounted on the shaft and provided with coupling teeth adapted to engage teeth on a collar 86 which is secured to the shaft. To avoid springing of the shaft at the points where the pressure is transmitted to the blade and to ensure an even and uniform pressure against the jacket, bearing blocks 38 are secured to the back-board to engage the upper side of th shaft adjacent the gears 18. The blocks are held on the backboard by bolts 10 and may be forced down and held in position by screws 42. The holes through which the bolts 40 pass are sufliciently large to permit vertical adjustment of the blocks to properly position or aline the gears. By adjustment of the weights the force tending to turn the shaft may be regulated to secure the requisite pressure be tween the edge of the blade and the jacket, and through the gears, racks and pressure plate uniform pressure is applied to the board at intervals so that it presses uniformly against the jacket. lneven pressure upon and uneven vearing of the jacket tending to shorten its life and impair its action on the paper stock is thus avoided.

While it is preferred to employ the specific construction and arrangement as shown and described, this construction and arrangement is not essential to the broader features of the invention and may be varied or modified as found desirable or best suited to the machine to which the guard-board is to be applied.

What is claimed is:

1. A guard-board for paper making machines comprising a thin jacket engaging blade of a thickness of approximately onefourth inch to maintain a bearing edge of uniformly efficient width to cooperate with the felt jacket of the couch roll as the blade wears away, a back-board on which the blade is mounted, and means for automatically maintaining the pressure of the blade against said jacket as the blade wears away.

2. A guard-board for paper making inachines comprising a jacket engaging blade, a back-board on which the blade is mounted for vertical movement, a shaft mounted on the back-board parallel to the blade, one or more weighted arms connected to the shaft, and a series of devices arranged at intervals along the shaft to transmit pressure from the shaft to the blade at intervals throughout its length.

3. A guard-board for paper making machines comprising a thin jacket-engaging blade having a uniform thickness substantially the same as the width of its bearing edge, a backboard on which the blade is mounted, means for maintaining the blade in sliding engagement with the backboard, and means for applying a uniform pressure throughout the length of the blade and automatically maintaining this pressure as the bearing edge wears away.

1. A guard-board for paper making machines comprising a thin jacket engaging blade having uniform thickness substantially the same as the width of its bearing edge, a back-board, retainers for holding and guiding the blade on the face of the board, a shaftparallel to the blade, a series of gears secured at intervals along the shaft, racks engaged by the gears and connected to transmit pressure to the blade, one or more arms on the shaft, and weights adjustable on the arms.

5. A guard-board for paper making machines comprising a backboard, a jacket-engaging blade guided thereon, a pressure plate engaging the upper edge of the blade throughout its length, means for retaining the blade in sliding engagement with'the backboard, and means for applying uniform pressure to the blade through the medium of the pressure plate and automatically maintaining the pressure substantially constant as the blade wears away.

6. A guard-board for paper making machines comprising a jacket engaging blade, a back-board on which the blade is mounted for vertical movement, a shaft mounted on the back-board parallel to the blade, one or more weighted arms connected with the shaft, a series of gears secured at intervals along the shaft, and racks engaged by the gears and connected to transmit pressure to the blade at intervals throughout its length.

7. A guard-board comprising a thin blade HOLDON M. ASHBY. 

